1. Field of the Invention
The present invention relates to a package substrate with a built-in capacitor on which a semiconductor device is mounted, and a manufacturing method thereof.
2. Description of the Prior Art
Conventionally, various structures of package substrates with built-in capacitors on which semiconductor devices are mounted have been proposed. In one proposed package substrate with a built-in capacitor, a thin-film capacitor is connected between a power supply line and a ground line to decouple the lines, whereby preventing an instantaneous potential drop of the power supply line due to switching noise caused by high-speed turning on and off of the mounted semiconductor device. For example, the Japanese Published Unexamined Patent Application No. 2001-68858 discloses, as shown in FIG. 16A and FIG. 16B, a package substrate 500 with a built-in capacitor in which the capacitor 550 including dielectric layers 502 mainly made of barium titanate and electrode layers 504 mainly made of palladium, are alternately laminated. The electrode layers 504 of the capacitor 550 include power supply layers 504a and ground layers 504b, and the power supply layers 504a and the ground layers 504b are alternately disposed. The power supply layers 504a are connected to each other by means of via conductors 505 and conducted to electrode pads 506 of the outermost layer, and the ground layers 504b are connected to each other by means of via conductors 507 and conducted to the ground pads 508 of the outermost layer. This capacitor 550 is disposed in a concave portion of the package substrate 500 with the built-in capacitor.